Mulhern is a sign of giant tool bag. Like really, if you looked up this name a giant picture of him would come up. A Mulhern is a man that goes through girls as quick as a fat kid goes through cake. People pretend to like Mulherns but only so they can make fun of him. He is the biggest D-Bag you will ever meet.

Girl to her friend: I met this guy last night and hes so sweet!
Guy: Ew are you serious?? That guy is such a Mulhern, no one should date him and no one likes him.